Mark wrote:

Or, for a totally different approach to calibration, how about an infrared thermometer.  Just point it at the thermostat housing and read the temp on the LCD readout.  Couldn't be any easier than that.

It’s true, they are easy, and a great way to go, but . . . you have to use with care.  I have one (different brand) that I borrowed from a racing friend who uses it to measure tire temps,.  They measure quite accurately (+- maybe 2%), and consistently, on a flat surface that is flat black.  On shiny curved surfaces your can get readings all over the place.  Also, the field of view expands with distance, so if you can’t get close enough, you may be reading lots of other stuff in the background.  I painted about 1” diameter spots with flat black paint where I want to measure, and get the thing about ½” away, and get good readings. On the curved surface of the pump outlet there is some variation unless held dead center.

Al